In recent years, as a recent activity of a wireless local area network (LAN) standard of the Institute of Electrical and Electronics Engineers, Inc. (IEEE) 802.11 (hereinafter, simply described as “802.11”), wireless LAN standards for increasing transmission capacity, such as 802.11b (a maximum of 11 Mbps (megabits per second)), 802.11a and 802.11g (a maximum of 54 Mbps), 802.11n (a maximum of 600 Mbps) and 802.11ac (a maximum of 6.9 Gbps (Gigabits per second)), have been added as a standard of a physical layer for indoor communication, for example.
Meanwhile, for example, a smart meter for implementing a smart grid has been examined in earnest, and there is a growing need for long-distance transmission at a low data transmission rate outdoors by use of the smart meter. The establishment of a new wireless LAN standard using a sub-GHz band, that is, a frequency bandwidth of less than 1 GHz has been studied, and the new standard includes assignment of available frequencies of a specific low-power radio device (for example, a smart meter). In the 802.11, Task Group (TG) ah which has studied a wireless LAN standard using a sub-GHz band was undertaken in 2010. As primary requirements for TGah, a data transmission rate is 100 kbps or more, and a maximum transmission distance is 1 km, for example.
In wireless LAN standards of task groups of the 802.11a and subsequent task groups using an orthogonal frequency division multiplexing (OFDM) signal, and also in TGah (802.11ah), a receiver establishes various synchronizations by using a preamble to be added to a header of a transmission packet, and performs burst communication. The preamble includes a short preamble used for automatic gain control (AGC) and automatic frequency control (AFC) for coarse tuning, and a long preamble for transmission channel estimation and fine-tuning AFC.
Patent Literature 1 suggests a method in which a receiving station detects a carrier frequency error in communication between a transmitting station and the receiving station by using the first transmission packet at the time of starting communication, and when the carrier frequency error between the transmitting and receiving stations is greater than a predetermined value, the carrier frequency error is corrected by using a detected value of the carrier frequency error at the time of receiving a subsequent transmission packet.